| 1. |
- Cao, Zhixing, et al.
(författare)
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Multi-scale data-driven engineering for biosynthetic titer improvement
- 2020
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Ingår i: Current Opinion in Biotechnology. - : Elsevier BV. - 0958-1669 .- 1879-0429. ; 65, s. 205-212
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Forskningsöversikt (refereegranskat)abstract
- Industrial biosynthesis is a very complex process which depends on a range of different factors, from intracellular genes and metabolites, to extracellular culturing conditions and bioreactor engineering. The identification of species that improve the titer of some reaction is akin to the task of finding a needle in a haystack. This review aims to summarize state-of-the-art biosynthesis titer improvement on different scales separately, particularly regarding the advancement of metabolic pathway rewiring and data-driven process optimization and control. By integrating multi-scale data and establishing a mathematical replica of a real biosynthesis, more refined quantitative insights can be gained for achieving a higher titer than ever.
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| 2. |
- Chen, Wenchuang, et al.
(författare)
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Experiments and CFD modeling of a dual-raft wave energy dissipator
- 2021
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018 .- 1873-5258. ; 237
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Tidskriftsartikel (refereegranskat)abstract
- A wave energy dissipator (WED) is proposed in this paper, composed of two asymmetric hinged floaters and two hydraulic cylinders, with the purpose to resist wave-induced relative rotation around the hinge. Experimental studies are performed to explore its performance under a wide range of regular waves. Based on Reynolds-averaged Navier-Stokes equations, a 3D numerical model is set up, considering the non-linear interaction of wave and WED. The agreement between the experimental and numerical results is good. With the validated numerical model, the influence of the WED geometrical factors on energy conversion and wave transmission is examined. For a given raft length, the difference in energy conversion between the two multiplicative inverse fore-and-aft raft lengths is significant, which is dependent on the wave frequency. However, as for the wave transmission, the difference in between is insignificantly small, almost independent of the wave frequency. The findings demonstrate that, for energy conversion, its maximum value per unit length corresponds to a large fore-and-aft length ratio but a small total raft length. The combination of experiments and simulations provides reference for both understanding of hydrodynamic behaviours and design including parameter selection of the dissipator.
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| 3. |
- Wei, Jianzheng, et al.
(författare)
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Design and testing of inflatable gravity-gradient booms in space
- 2020
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Ingår i: CEAS Space Journal. - : SPRINGER WIEN. - 1868-2502 .- 1868-2510. ; 12:1, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- Inflatable space structures have many advantages such as small size, high reliability, and low cost. Aiming at a gravity-gradient boom for an XY-1 satellite, New Technology Verifying Satellite-1, a slender inflatable boom with low magnetic is presented. First of all, an inflatable boom with six self-supporting thin shells made of carbon and Vectran fiber composite materials on the inner wall was designed for eliminating a magnetic dipole moment and increasing structural stiffness. A precise stowage was designed for a tip mass surrounded by a pair of lightweight honeycomb blocks added on the top of the boom. The stowed boom was tested by sine sweep vibrations with three directions on the ground to verify the reasonable design. The XY-1 satellite which carried the inflatable boom was launched into low orbit. After being stowed state in space for at least 6 months, the inflatable boom orderly unfolded a 2.0 kg tip mass to 3.0 m away in May, 2013. The inflatable boom was successfully deployed from a series of photographs received on the satellite. The results show that this kind of lightweight inflatable boom with self-supporting thin shells can orderly unfold and fulfil the function of gravity-gradient in space for a long time.
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| 4. |
- Wei, Jianzheng, et al.
(författare)
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Modal analysis and identification of deployable membrane structures
- 2018
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Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 152, s. 811-822
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Tidskriftsartikel (refereegranskat)abstract
- The development of ultra-lightweight sails presents many challenges due to their large size and extreme flexibility. One of their key technologies is the design of deployable booms, in particular how to deploy and support the membrane structure. In this paper, a deployable sail with four triangular membranes supported by inflated booms enhanced by four self-supporting thin shells inside and Velcro outside is presented. The feasibility of the folding and unfolding processes is demonstrated, and their modal properties investigated. Firstly, the pressure variation and acceleration time history of a single boom during unfolding process were obtained by dynamic testing system, a finite element model of boom was proposed and structural natural frequencies by simulation were validated by experimental testing. Further, an 8.0 x 8.0 m(2) prototype was assembled and stowed in a Phi 700 mm by 300 mm container, and the structure was fully deployed with gas control. A finite element model of a combination of inflatable booms and triangular membranes was used to predict the structural overall bending modes. The effect of membrane wrinkling was simulated and controlled to improve membrane precision. This work validated the concept of deployable membrane structural design. The proposed finite element models were verified by experimental testing to be useful for membrane structure analysis.
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| 5. |
- Wei, Jianzheng, et al.
(författare)
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Quasi-static folding and deployment of rigidizable inflatable beams
- 2021
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Ingår i: International Journal of Solids and Structures. - : Elsevier BV. - 0020-7683 .- 1879-2146. ; 232
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Tidskriftsartikel (refereegranskat)abstract
- This paper is concerned with a theoretical and experimental study of the deployment of inflated curved slender beams. A theoretical model for a beam with effects from restoring force and moment on deployment angle is proposed. Assuming slow deployment, a quasi-static viewpoint is utilized to simplify the model which the buckling cross-section is considered. The relation between deployment angle and contact area at the instability bending point is studied for the membrane chamber of a thermally rigidizable inflatable beam. While an inflated beam was constrained as simply-supported and fixed-free at its ends, the relations between the restoring force and moment and the internal pressure and its angle were tested by adding to the mechanical experimental method an infrared thermal imager. Results show that the restoring force and moment are increasing with the pressure at a given angle. Moreover, the restoring moment is nonlinearly related to the deployment angle. The correctness of the theoretical model was verified through experiments.
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| 6. |
- Wu, Jinming, et al.
(författare)
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Performance analysis of solo Duck wave energy converter arrays under motion constraints
- 2017
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 139, s. 155-169
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the power capture performance of solo Duck wave energy converter (WEC) arrays. The barrier function method combined with a quasi-Newton BFGS optimization algorithm is applied to find the maximum captured power of the array when the Ducks are under motion constraints. Based on this optimized maximum captured power, the effects of separation distance, wave period, incident wave direction and Duck width on the array performance are investigated. For the two Ducks array, results show that the alternative constructive and destructive interaction stripes in the contour plot of the q-factor variation with non-dimensional separation distance are resulted from the diffracted wave pattern from each Duck, and the hydrodynamic interaction strength is reduced when constraints affect the performance. For the three Ducks array, the middle Duck shows larger variability of captured power than the side Ducks due to experiencing double in phase diffracted wave from the side ones. The captured power of the solo Duck WEC array is sensitive to incident wave direction, and arrays with Ducks of smaller width are found to have better performance in power capture efficiency.
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| 7. |
- Yao, Huifeng, et al.
(författare)
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14.7% Efficiency Organic Photovoltaic Cells Enabled by Active Materials with a Large Electrostatic Potential Difference
- 2019
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 141:19, s. 7743-7750
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Tidskriftsartikel (refereegranskat)abstract
- Although significant improvements have been achieved for organic photovoltaic cells (OPVs), the top-performing devices still show power conversion efficiencies far behind those of commercialized solar cells. One of the main reasons is the large driving force required for separating electron-hole pairs. Here, we demonstrate an efficiency of 14.7% in the single-junction OPV by using a new polymer donor PTO2 and a nonfullerene acceptor IT-4F. The device possesses an efficient charge generation at a low driving force. Ultrafast transient absorption measurements probe the formation of loosely bound charge pairs with extended lifetime that impedes the recombination of charge carriers in the blend. The theoretical studies reveal that the molecular electrostatic potential (ESP) between PTO2 and IT-4F is large, and the induced intermolecular electric field may assist the charge generation. The results suggest OPVs have the potential for further improvement by judicious modulation of ESP.
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| 8. |
- Yao, Huifeng, et al.
(författare)
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Critical Role of Molecular Electrostatic Potential on Charge Generation in Organic Solar Cells
- 2018
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Ingår i: Chinese journal of chemistry. - : WILEY-V C H VERLAG GMBH. - 1001-604X .- 1614-7065. ; 36:6, s. 491-494
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Tidskriftsartikel (refereegranskat)abstract
- Revealing the charge generation is a crucial step to understand the organic photovoltaics. Recent development in non-fullerene organic solar cells (OSCs) indicates efficient charge separation even with negligible energetic offset between the donor and acceptor materials. These new findings trigger a critical question concerning the charge separation mechanism in OSCs, traditionally believed to result from sufficient energetic offset between the polymer donor and fullerene acceptor. We propose a new mechanism, which involves the molecular electrostatic potential, to explain efficient charge separation in non-fullerene OSCs. Together with the new mechanism, we demonstrate a record efficiency of similar to 12% for systems with negligible energetic offset between donor and acceptor materials. Our analysis also rationalizes different requirement of the energetic offset between fullerene-based and non-fullerene OSCs, and paves the way for further design of OSC materials with both high photocurrent and high photovoltage at the same time.
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| 9. |
- Zhang, Yan, 1976, et al.
(författare)
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Experimental and Numerical Investigations on the Performance and Reliability of CNT Fins for Micro-Cooler
- 2012
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Ingår i: Proceedings of IEEE CPMT 2012 International Conference on Electronic Packaging Technology & High Density Packaging. - 9781467316804 ; , s. 1573-1577
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Konferensbidrag (refereegranskat)abstract
- The current development of electronic products towards miniaturization and multifunction is leading to an increase in the power density of chip and IC. The high power consumption and corresponding heat dissipation are two of the most serious limitations for high performance electronics. The combination of the carbon nanotube (CNT) with outstanding thermal properties with an air jet cooling provides a promising option for the heat dissipation of high-powered components and devices. In the present paper, the CNTs are utilized to manufacture the pin-fins for the micro-cooler, and the performance and evaluation of this CNT-based micro-pin-fin cooler are investigated both experimentally and numerically. The effects of various parameters, such as the jet velocity and height, the fin size and shape, and so on, on the flow field and temperature distribution characteristics are comprehensively considered and analyzed. The obtained results indicate that the CNT-fins are of quite good strength and thermal performance in the jet impingement cooling environment. © 2012 IEEE.
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